concur about it being there seemingly forever...first time I ever saw it in operation was sometime around 1995 or 1996. Was helping someone move from AZ and so I was in a big uHaul van with her blonde-blue-eyed daughter in the front seat as we roll in there around 2AM.
We got asked precisely one question- "are y'all American citizens." As I responded yes, we were waved on through.
Some of our quick wave might have been that the vehicle in front of us was not doing so well at following directions and was about to get a full content search as a result...
Still was very surprised that a moving van in the middle of the night was NOT subjected to at least a pull to the side and open the back sort of check...